Self-(In)compatibility Systems: Target Traits for Crop-Production, Plant Breeding, and Biotechnology

Abstract

Self-incompatibility (SI) mechanisms prevent self-fertilization in flowering plants based on specific discrimination between self-and non-self pollen. Since this trait promotes outcrossing and avoids inbreeding it is a widespread mechanism of controlling sexual plant reproduction. Growers and breeders have effectively exploited SI as a tool for manipulating domesticated crops for thousands of years. However, only within the past thirty years have studies begun to elucidate the underlying molecular features of SI. The specific S-determinants and some modifier factors controlling SI have been identified in the sporophytic system exhibited by Brassica species and in the two very distinct gametophytic systems present in Papaveraceae on one side and in Solanaceae, Rosaceae, and Plantaginaceae on the other. Molecular level studies have enabled SI to SC transitions (and vice versa) to be intentionally manipulated using marker assisted breeding and targeted approaches based on transgene integration, silencing, and more recently CRISPR knock-out of SI-related factors. These scientific advances have, in turn, provided a solid basis to implement new crop production and plant breeding practices. Applications of self-(in)compatibility include widely differing objectives such as crop yield and quality improvement, marker-assisted breeding through SI genotyping, and development of hybrids for overcoming intra-and interspecific reproductive barriers. Here, we review scientific progress as well as patented applications of SI, and also highlight future prospects including further elucidation of SI systems, deepening our understanding of SI-environment relationships, and new perspectives on plant self/non-self recognition.

Characterization and practical use of self-compatibility in outcrossing grass species

“…Physiological SI mechanisms can be classified as gametophytic or sporophytic, but the specific mechanisms, as well as the number of genetic determinants involved, vary between families. Identification of SI-determinant genes has only been achieved for SI systems controlled by a single locus, called S , such as those of the Solanaceae, Rosaceae, Plantaginaceae, Brassicaceae and Papaveraceae, discussed in detail in a recent review ( Muñoz-Sanz et al , 2020 ). Despite the involvement of different molecular actors, the underlying genetic principles of all single-locus SI systems are similar.…”

RNase‐based self‐incompatibility in cacti

“…Synthesis of such knowledge can be used to precisely detect convergence – independent re‐evolution of alternative SI mechanisms – help to identify when, where and how often it occurred, as well as to infer the general factors that cause evolutionary innovation. Finally, a better understanding of SI mechanisms allows manipulations to reduce mate limitation and increase fruit set, with direct applications ranging from plant conservation (Mandujano et al ., 2010) to agriculture (Muñoz‐Sanz et al ., 2020).…”

Candidate gene mapping identifies genomic variations in the fire blight susceptibility genes HIPM and DIPM across the Malus germplasm

“…Wild Malus species often have poor fruit quality and it can take up to 25–30 years to fully recover fruit quality and eliminate linkage drag of undesirable alleles in a Malus domestica background 8 . Self-incompatibility and high heterozygosity also make breeding outside of M. domestica not feasible in many cases 9 . Thus, within this context, developing sequence-based markers and using them in targeted MAS can greatly reduce the length of breeding schemes.…”